The closing laps to Monaco 2011 is my favorite F1 race, Vettel in the lead on old tires, Alonso catching with fresh tires, Button catching even harder on fresher tires, all three nose to tail with 5 laps to go was going to be spectacular.
Then Petrov stuffed it into a wall, red flag came out and the FIA said it was ok to change your tires and we returned to 5 of the most frustrating parade laps of my life.
Monaco is usually pretty boring though, it's exciting to see guys run around the track at full bore but after that it's just a parade with some pit stops and a collision or two (well, maybe 3 or 4 with Maldonado on track.)